Luxeon LEDs have the potential to out shine Halogen or Xenon lamps of similar, or even a bit higher wattage. However, it takes good current delivery and heat sinking to achieve this, and unfortunately I have not seen this in a dive light (yet). The Tek-Tite Lux lights are using a PR based Luxeon LED lamp module (basically a bulb replacement) with very poor heat sinking. As such they are under driven and not very bright. They do give loooong run time on a set of batteries, though.
The UK 4AA eLED is a bit better. Brighter than the Tek-Tite lights, and good power regulation. Still not a retina scorcher, but a nice light. The incadescent version is a lot brighter, but the LED version will run for 18 hours (+) at full brightness, and a lot longer at reduced levels.
The UK eLED C4 & C8 are running the 5W Luxeon Portable emitter and should be very nice. I have not recieved mine yet (this week, I hope) so I can't give you any first hand experience yet. A review I've seen said that in the C4 it was a bit under driven, but still quite bright. The C8 version was both brighter and had significantly longer run time. The reviewer tested with Alkaline batteries which are poor for high current delivery (which a regulated 5W Luxeon would need), so I would bet the C4 would do better with rechargeable NiMh batteries. Will let you know when I get mine.
One of the things that bugs me about all these new LED lights is the claims from the companies advertising. Things like 100,000 hours life; ultra reliable; shock proof; virtually indestructable; and other crap like that.
First of all, those 100,000 hour life claims are typically for the smaller, dimmer LEDs, and if you look at the specs, often that life is rated to 25% (or less) of the initial brightness. Unfortunately, many advertisers take the specs for the small, dim LEDs and apply them to the higher power ones, which is just plain wrong (high power LEDs have much shorter run time specs).
Even with the smaller LEDs, those specs are for LEDs that are driven at a very specific power level and carefully regulated. Lights almost always over-drive small LEDs and usually have poor power regulation (when they have it at all). This affects the reliability of the LED significantly. Tek-Tite in particular had a lot of problems with burned out LED modules in their early lights. Their newer lights don't drive the LEDs as hard and are much more reliable.
As for the high power (Luxeon) LED, the big problem in a dive light is heat sinking. Halogen/Xenon lamps are designed to run hot (in fact they have to run hot for the halogen scavenging action) so dive lights are designed to survive this heat without melting (usually), but have not been designed to transfer this heat out of the light. Currently all but one of the LED dive lights I have seen are simply older incandescent models retrofitted with LED light modules. This means very poor heat sinking, and a big problem for high power LED modules. When the LED runs hot it will produce a lot less light and will have a much shorter life. In my experimenting with a 1W Luxeon I found that light output would drop to 50% or less after only a few minutes with poor heat sinking.
To really take advantage of this new high power LED technology, dive lights will need a major re-design. Thermally condcutive polymers or metal housings to keep the LED cool is a must. I have only seen this in custom made lights so far.
Of the lights that are currently available, the UK 4AA eLED seems to be a nice light. A bit under-driven for reliability over brightness, and good power regulation for looooong run time. The C4/C8 5W models have potential. The larger head of the C4/C8 could provide better heat sinking, if the module is well designed. Heat transfer out through the plastic body will still be a problem, though. We'll see when I get mine...
The Pelican LED models also seem to be well regarded (but I don't have any first hand experience with them).
Most of the PR style replacement lamps are disappointing. Poor heat sinking requires them to be under-driven, and both brightness and longevity suffer. The best of the PR lamp replacements is probably the EverLED from LED Dynamics. It is a 1W Luxeon side emitter (focusable in lights that have this feature). It has a built-in buck/boost regulation circuit that allows it to run with 1 to 6 cell lights (1.5V to 9V). It is driven pretty close to spec so it is fairly bright, but is has a temperature regulation circuit so brightness can and will drop off if the light doesn't provide good heat transfer. Reliability has been good, but not perfect. They are pretty shock proof, and will even continue to function if your light floods. The weakness seems to be in the regulation circuit itself. I have had one fail, and I know a few other people who have had them fail as well. So while they are quite durable and reliable, they are not the indestructable, run-forever marvels that the advertising would have you believe.
So where do we stand with this new technology? As a primary dive light I think there is a lot of room, and need for improvement. The UK C8 eLED has been getting favorable reviews and is probably the only real option in a production light.
As backup light source, the UK 4AA eLED would be a good option. An EverLED in a host like a Tec40 or one of the smaller Ikelites would also make a nice backup light.
Hope this info helps...
Aloha, iG
